Steering input apparatus for trailer backup assist system

ABSTRACT

A trailer backup steering input apparatus provides a trailer steering information signal to a trailer backup assist control module of a vehicle through a signal interface thereof. The trailer steering information signal is configured for enabling the trailer backup assist control module to generate electrical steering commands for a steering system of the vehicle as a function of the trailer steering information signal. The trailer backup steering input apparatus is self-contained and physically detachable/detached form the vehicle. Advantageously, such a trailer backup steering input apparatus saves space, allows for greater flexibility with interior styling of the vehicle, and allows all drivers regardless of stature the ability to have the trailer backup steering input apparatus easily accessible while utilizing the trailer backup assist functionality of the vehicle.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation-in-part application ofco-pending U.S. Non-provisional patent application which has Ser. No.13/443,743, which was filed Apr. 10, 2012, which is entitled “DETECTIONOF AND COUNTER-MEASURES FOR JACKKNIFE ENABLING CONDITIONS DURING TRAILERBACKUP ASSIST”, and which has a common applicant herewith and is beingincorporated herein in their entirety by reference.

FIELD OF THE DISCLOSURE

The disclosures made herein relate generally to steering assisttechnologies in vehicles and, more particularly, to trailer backupassist system having a driver interface and system for controlling aradius of curvature for a trailer path.

BACKGROUND

It is well known that backing up a vehicle with a trailer attached is adifficult task for many drivers. This is particularly true for driverswho are untrained at backing with trailers such as, for example, thosewho drive with an attached trailer on an infrequent basis (e.g., haverented a trailer, use a personal trailer on an infrequent basis, etc).One reason for such difficulty is that backing a vehicle with anattached trailer requires counter-steering that is opposite to normalsteering when backing the vehicle without a trailer attached and/orrequires braking to stabilize the vehicle-trailer combination before ajack-knife condition occurs. Another reason for such difficulty is thatsmall errors in steering while backing a vehicle with an attachedtrailer are amplified, thereby causing the trailer to depart from adesired path.

To assist the driver in steering a vehicle with trailer attached, atrailer backup assist system needs to know the driver's intention. Onecommon assumption with known trailer backup assist systems is that adriver of a vehicle with an attached trailer wants to back up straightand the system either implicitly or explicitly assumes a zero curvaturepath for the vehicle-trailer combination. Unfortunately most ofreal-world use cases of backing a trailer involve a curved path and,thus, assuming a path of zero curvature would significantly limitusefulness of the system. Some known systems assume that a path is knownfrom a map or path planner. To this end, some known trailer backupassist systems operate under a requirement that a trailer back-up pathis known before backing of the trailer commences such as, for example,from a map or a path planning algorithm. Undesirably, suchimplementations of the trailer backup assist systems are known to have arelatively complex Human Machine Interface (HMI) to specify the path,obstacles and/or goal of the backup maneuver. Furthermore, such systemsalso require some way to determine how well the desired path is beingfollowed and to know when the desired goal, or stopping point andorientation, has been met, using approaches such as cameras, inertialnavigation, or high precision GPS. These requirements lead to arelatively complex and costly system.

As previously mentioned, one reason backing a trailer can prove to bedifficult is the need to control the vehicle in a manner that limits thepotential for a jack-knife condition to occur. A trailer has attained ajackknife condition when a hitch angle cannot be reduced (i.e., madeless acute) by application of a maximum steering input for the vehiclesuch as, for example, by moving steered front wheels of the vehicle to amaximum steered angle at a maximum rate of steering angle change. In thecase of the jackknife angle being achieved, the vehicle must be pulledforward to relieve the hitch angle in order to eliminate the jackknifecondition and, thus, allow the hitch angle to be controlled viamanipulation of the steered wheels of the vehicle. However, in additionto the jackknife condition creating the inconvenient situation where thevehicle must be pulled forward, it can also lead to damage to thevehicle and/or trailer if certain operating conditions of the vehiclerelating to its speed, engine torque, acceleration, and the like are notdetected and counteracted. For example, if the vehicle is travelling ata suitably high speed and/or subjected to a suitably high longitudinalacceleration when the jackknife condition is achieved, the relativemovement of the vehicle with respect to the trailer can lead to contactbetween the vehicle and trailer thereby damaging the trailer and/or thevehicle.

Therefore, an approach for backing a trailer that provides a simplehuman machine interface and that overcomes other shortcomings of knowntrailer backup assist systems would be advantageous, desirable anduseful.

SUMMARY OF THE DISCLOSURE

Embodiments of the inventive subject matter are directed toimplementation of a trailer backup steering input apparatus that isself-contained and physically detached from or detachable from avehicle. By being self-contained and physically detached from ordetachable from the vehicle, a trailer backup steering input apparatusconfigured in accordance with the inventive subject matter allows adriver of the vehicle to dictate its placement so as to optimize theoverall effectiveness and preference in operation of a trailer back-upassist (TBA) system of the vehicle. In this manner, embodiments of theinventive subject matter overcome the adverse issues associated with atrailer backup steering input apparatus being permanently mounted on thevehicle at a specific fixed location (e.g., fixedly integrated into thevehicle). One such adverse issue can be the amount of physical spacewithin the vehicle that is occupied by a permanently mounted trailerbackup steering input apparatus. Another such adverse issues can be thata permanently mounted trailer backup steering input apparatus may notmeet styling or design guidelines for the vehicle (e.g., due to itsaesthetic appearance). Still another such adverse issue can be that apermanently mounted trailer backup steering input apparatus may belocated at a position that is awkward for some drivers to use (e.g., ata position that requires a driver to lean forward therefore putting themin a difficult position to monitor the trailer in the mirrors of thevehicle).

In one embodiment of the inventive subject matter, a trailer backupsteering input apparatus provides a trailer steering information signalto a trailer backup assist control module of a vehicle through a signalinterface thereof. The trailer steering information signal is configuredfor enabling the trailer backup assist control module to generateelectrical steering commands for a steering system of the vehicle as afunction of the trailer steering information signal. The trailer backupsteering input apparatus comprises a user interface, a signal generator,a signal interface, and an enclosure. Trailer path altering commands areinputted through the user interface. The signal generator generates thetrailer steering information signal as a function of the trailer pathaltering commands. The signal interface is connectable to the signalinterface of the trailer backup assist control module for enabling thetrailer steering information signal to be transmitted from the trailerbackup steering input apparatus for reception by the trailer backupassist control module. The enclosure has the user interface, the signalgenerator, and the signal interface mounted thereon such that thetrailer backup steering input apparatus is able to be selectively placedby a driver of the vehicle with respect to a structure to which thetrailer backup assist control module is mounted.

In another embodiment of the inventive subject matter, a trailer backupassist system comprises a trailer backup assist control module and atrailer backup steering input apparatus. The trailer backup assistcontrol module has a set of instructions tangibly embodied on anon-transitory processor-readable medium thereof. The set ofinstructions is accessible from the non-transitory processor-readablemedium by at least one data processing device of the electroniccontroller system for being interpreted thereby. The set of instructionsis configured for causing the at least one data processing device tocarry out operations for receiving trailer path curvature informationcharacterizing a desired curvature for a path of travel of a trailerduring backing of the trailer by a vehicle towably coupled thereto,determining vehicle steering information through assessment ofkinematical information of a system defined by the vehicle and thetrailer, and generating a steering command for a steering system of thevehicle as a function of the vehicle steering information. The trailerpath curvature information includes trailer steering information andtrailer angle information. Assessment of the kinematical information isperformed as a function of the trailer path curvature information. Thetrailer backup steering input apparatus is configured for enabling thetrailer steering information to be provided to the trailer backup assistcontrol module. The trailer backup steering input apparatus isself-contained and electronically connectable to the trailer backupassist control module in a manner enabling selective placement of thetrailer backup steering input apparatus by a driver of the vehicle withrespect to a structure to which the trailer backup assist control moduleis mounted.

In another embodiment of the inventive subject matter a vehiclecomprises a trailer backup assist control module, a steering system, anda trailer backup steering input apparatus. The trailer backup assistcontrol module is configured for generating electrical steering commandsas a function of trailer path curvature information. The trailer pathcurvature information characterizes a desired curvature for the path oftravel of a trailer during backing of the trailer by a vehicle towablycoupled thereto. The trailer path curvature information includes trailersteering information and trailer angle information. The trailer backupassist control module includes a signal interface for receiving thetrailer steering information. The steering system is coupled to thetrailer backup assist control module for receiving steering assistcontrol signals therefrom. The steering system controls actuationmechanisms thereof as a function of the steering assist control signals.The trailer backup steering input apparatus is configured for enablingthe trailer steering information to be provided to the trailer backupassist control module through the signal interface. The trailer backupsteering input apparatus is self-contained and electronically connectedto the trailer backup assist control module in a manner enablingselective placement of the trailer backup steering input apparatus by adriver of the vehicle with respect to a structure of the vehicle towhich the trailer backup assist control module is mounted.

These and other objects, embodiments, advantages and/or distinctions ofthe inventive subject matter will become readily apparent upon furtherreview of the following specification, associated drawings and appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a vehicle configured for performing trailer backup assistfunctionality in accordance with an embodiment of the inventive subjectmatter embodiment.

FIG. 2 shows a preferred embodiment of the trailer backup steering inputapparatus discussed in reference to FIG. 1.

FIG. 3 shows an example of a trailer backup sequence implemented usingthe trailer backup steering input apparatus discussed in reference toFIG. 2.

FIG. 4 shows a method for implementing trailer backup assistfunctionality in accordance with an embodiment of the inventive subjectmatter.

FIG. 5 is a diagrammatic view showing a kinematic model configured forproviding information utilized in providing trailer backup assistfunctionality in accordance with the inventive subject matter.

FIG. 6 is a graph showing an example of a trailer path curvaturefunction plot for a rotary-type trailer backup steering input apparatusconfigured in accordance with the inventive subject matter.

FIG. 7 is a diagrammatic view showing a relationship between hitch angleand steered angle as it relates to determining a jackknife angle for avehicle/trailer system.

FIG. 8 shows a method for implementing jackknife countermeasuresfunctionality in accordance with an embodiment of the inventive subjectmatter.

FIG. 9 is a diagrammatic view showing a self-contained and selectivelyplacable implementation of a trailer backup steering input apparatus inaccordance with the inventive subject matter.

DETAILED DESCRIPTION OF THE DRAWING FIGURES

The inventive subject matter is directed to providing trailer backupassist functionality. In particular, such trailer backup assistfunctionality is directed to implementing one or more countermeasuresfor limiting the potential of a jackknife condition being attainedbetween a vehicle and a trailer being towed by the vehicle. In certainembodiments of the inventive subject matter, curvature of a path oftravel of the trailer (i.e., trailer path curvature control) can becontrolled by allowing a driver of the vehicle to specify a desired pathof the trailer by inputting a desired trailer path curvature as thebackup maneuver of the vehicle and trailer progresses. Although acontrol knob, a set of virtual buttons, or a touch screen can each beimplemented for enabling trailer path curvature control, the inventivesubject matter is not unnecessarily limited to any particularconfiguration of interface through which a desired trailer pathcurvature is inputted. Furthermore, in the case where a steering wheelcan be mechanically decoupled from steered wheels of the vehicle, thesteering wheel can also be used as an interface through which a desiredtrailer path curvature is inputted. As will be discussed herein ingreater detail, kinematical information of a system defined by thevehicle and the trailer are used to calculate a relationship (i.e.,kinematics) between the trailer's curvature and the steering angle ofthe vehicle for determining steering angle changes of the vehicle forachieving the specified trailer path. Steering commands corresponding tothe steering angle changes are used for controlling a steering system ofthe vehicle (e.g., electric power assisted steering (SPAS) system) ofthe vehicle for implementing steering angle changes of steered wheels ofthe vehicle to achieve (e.g., to approximate) the specified path oftravel of the trailer.

Referring to FIG. 1, an embodiment of a vehicle 100 configured forperforming trailer backup assist functionality in accordance with theinventive subject matter is shown. A trailer backup assist system 105 ofthe vehicle 100 controls the curvature of path of travel of the trailer110 that is attached to the vehicle 100. Such control is accomplishedthrough interaction of a power assisted steering system 115 of thevehicle 100 and the trailer backup assist system 105. During operationof the trailer backup assist system 105 while the vehicle 100 is beingreversed, a driver of the vehicle 100 is sometimes limited in the mannerin which he/she can make steering inputs via a steering wheel of thevehicle 100. This is because in certain vehicles the trailer backupassist system 105 is in control of the power assisted steering system115 and the power assisted steering system 115 is directly coupled tothe steering wheel (i.e., the steering wheel of the vehicle 100 moves inconcert with steered wheels of the vehicle 100). As is discussed belowin greater detail, a human machine interface (HMI) of the backup assistsystem 105 is used for commanding changes in curvature of a path of thetrailer 110 such as a knob, thereby decoupling such commands from beingmade at the steering wheel of the vehicle 100. However, some vehiclesconfigured to provide trailer backup assist functionality in accordancewith the inventive subject matter will have the capability toselectively decouple steering movement from movement of steerable wheelsof the vehicle, thereby allowing the steering wheel to be used forcommanding changes in curvature of a path of a trailer during suchtrailer backup assist.

The trailer backup assist system 105 includes a trailer backup assistcontrol module 120, a trailer backup steering input apparatus 125, and ahitch angle detecting apparatus 130. The trailer backup assist controlmodule 120 is connected to the trailer backup steering input apparatus125 and the hitch angle detecting apparatus 130 for allowingcommunication of information there between. It is disclosed herein thatthe trailer backup steering input apparatus can be coupled to thetrailer backup assist control module 120 in a wired or wireless manner.The trailer backup assist system control module 120 is attached to apower-steering assist control module 135 of the power-steering assistsystem 115 for allowing information to be communicated therebetween. Asteering angle detecting apparatus 140 of the power-steering assistsystem 115 is connected to the power-steering assist control module 125for providing information thereto. The trailer backup assist system isalso attached to a brake system control module 145 and a powertraincontrol module 150 for allowing communication of informationtherebetween. Jointly, the trailer backup assist system 105, thepower-steering assist system 115, the brake system control module 145,the powertrain control module 150 define a trailer backup assistarchitecture configured in accordance with an embodiment of theinventive subject matter.

The trailer backup assist control module 120 is configured forimplementing logic (i.e., instructions) for receiving information fromthe trailer backup steering input apparatus 125, the hitch angledetecting apparatus 130, the power-steering assist control module 135,the brake system control module 145, and the powertrain control module150. The trailer backup assist control module 120 (e.g., a trailercurvature algorithm thereof) generates vehicle steering information as afunction of all or a portion of the information received from thetrailer backup steering input apparatus 125, the hitch angle detectingapparatus 130, the power-steering assist control module 135, the brakesystem control module 145, and the powertrain control module 150.Thereafter, the vehicle steering information is provided to thepower-steering assist control module 135 for affecting steering of thevehicle 100 by the power-steering assist system 115 to achieve acommanded path of travel for the trailer 110.

The trailer backup steering input apparatus 125 provides the trailerbackup assist control module 120 with information defining the commandedpath of travel of the trailer 110 to the trailer backup assist controlmodule 120 (i.e., trailer steering information). The trailer steeringinformation can include information relating to a commanded change inthe path of travel (e.g., a change in radius of path curvature) andinformation relating to an indication that the trailer is to travelalong a path defined by a longitudinal centerline axis of the trailer(i.e., along a substantially straight path of travel). As will bediscussed below in detail, the trailer backup steering input apparatus125 preferably includes a rotational control input device for allowing adriver of the vehicle 100 to interface with the trailer backup steeringinput apparatus 125 to command desired trailer steering actions (e.g.,commanding a desired change in radius of the path of travel of thetrailer and/or commanding that the trailer travel along a substantiallystraight path of travel as defined by a longitudinal centerline axis ofthe trailer). In a preferred embodiment, the rotational control inputdevice is a knob rotatable about a rotational axis extending through atop surface/face of the knob. In other embodiments, the rotationalcontrol input device is a knob rotatable about a rotational axisextending substantially parallel to a top surface/face of the knob.

Some vehicles (e.g., those with active front steer) have apower-steering assist system configuration that allows a steering wheelto be decoupled from movement of the steered wheels of such a vehicle.Accordingly, the steering wheel can be rotated independent of the mannerin which the power-steering assist system of the vehicle controls thesteered wheels (e.g., as commanded by vehicle steering informationprovided by to a power-steering assist system control module from atrailer backup assist system control module configured in accordancewith an embodiment of the inventive subject matter). As such, in thesetypes of vehicles where the steering wheel can be selectively decoupledfrom the steered wheels to allow independent operation thereof, trailersteering information of a trailer backup assist system configured inaccordance with the inventive subject matter can be provided throughrotation of the steering wheel. Accordingly, it is disclosed herein thatin certain embodiments of the inventive subject matter, the steeringwheel is an embodiment of a rotational control input device in thecontext of the inventive subject matter. In such embodiments, thesteering wheel would be biased (e.g., by an apparatus that isselectively engagable/activatable) to an at-rest position betweenopposing rotational ranges of motion.

The hitch angle detecting apparatus 130, which operates in conjunctionwith a hitch angle detection component 155 of the trailer 110, providesthe trailer backup assist control module 120 with information relatingto an angle between the vehicle 100 and the trailer 110 (i.e., hitchangle information). In a preferred embodiment, the hitch angle detectingapparatus 130 is a camera-based apparatus such as, for example, anexisting rear view camera of the vehicle 100 that images (i.e., visuallymonitors) a target (i.e., the hitch angle detection component 155)attached the trailer 110 as the trailer 110 is being backed by thevehicle 100. Preferably, but not necessarily, the hitch angle detectioncomponent 155 is a dedicated component (e.g., an item attachedto/integral with a surface of the trailer 110 for the express purpose ofbeing recognized by the hitch angle detecting apparatus 130).Alternatively, the hitch angle detecting apparatus 130 can be a devicethat is physically mounted on a hitch component of the vehicle 100and/or a mating hitch component of the trailer 110 for determining anangle between centerline longitudinal axes of the vehicle 100 and thetrailer 110. The hitch angle detecting apparatus 130 can be configuredfor detecting a jackknife enabling condition and/or related information(e.g., when a hitch angle threshold has been met).

The power-steering assist control module 135 provides the trailer backupassist control module 120 with information relating to a rotationalposition (e.g., angle) of the steering wheel angle and/or a rotationalposition (e.g., turning angle(s)) of steered wheels of the vehicle 100.In certain embodiments of the inventive subject matter, the trailerbackup assist control module 120 can be an integrated component of thepower steering assist system 115. For example, the power-steering assistcontrol module 135 can include a trailer back-up assist algorithm forgenerating vehicle steering information as a function of all or aportion of information received from the trailer backup steering inputapparatus 125, the hitch angle detecting apparatus 130, thepower-steering assist control module 135, the brake system controlmodule 145, and the powertrain control module 150.

The brake system control module 145 provides the trailer backup assistcontrol module 120 with information relating to vehicle speed. Suchvehicle speed information can be determined from individual wheel speedsas monitored by the brake system control module 145. In some instances,individual wheel speeds can also be used to determine a vehicle yawangle and/or yaw angle rate and such yaw angle and/or yaw angle rate canbe provided to the trailer backup assist control module 120 for use indetermining the vehicle steering information. In certain embodiments,the trailer backup assist control module 120 can provide vehicle brakinginformation to the brake system control module 145 for allowing thetrailer backup assist control module 120 to control braking of thevehicle 100 during backing of the trailer 110. For example, using thetrailer backup assist control module 120 to regulate speed of thevehicle 100 during backing of the trailer 110 can reduce the potentialfor unacceptable trailer backup conditions. Examples of unacceptabletrailer backup conditions include, but are not limited to, a vehicleoverspeed condition, trailer angle dynamic instability, a trailerjack-knife condition as defined by an angular displacement limitrelative to the vehicle 100 and the trailer 110, and the like. It isdisclosed herein that the backup assist control module 120 can issue asignal corresponding to a notification (e.g., a warning) of an actual,impending, and/or anticipated unacceptable trailer backup condition.

The powertrain control module 150 interacts with the trailer backupassist control module 120 for regulating speed and acceleration of thevehicle 100 during backing of the trailer 110. As mentioned above,regulation of the speed of the vehicle 100 is necessary to limit thepotential for unacceptable trailer backup conditions such as, forexample, jack-knifing and trailer angle dynamic instability. Similar tohigh-speed considerations as they relate to unacceptable trailer backupconditions, high acceleration can also lead to such unacceptable trailerbackup conditions.

Referring now to FIG. 2, a preferred embodiment of the trailer backupsteering input apparatus 125 discussed in reference to FIG. 1 is shown.A rotatable control element in the form of a knob 170 is coupled to amovement sensing device 175. The knob 170 is biased (e.g., by a springreturn) to an at-rest position P(AR) between opposing rotational rangesof motion R(R), R(L). A first one of the opposing rotational ranges ofmotion R(R) is substantially equal to a second one of the opposingrotational ranges of motion R(L), R(R). To provide a tactile indicationof an amount of rotation of the knob 170, a force that biases the knob170 toward the at-rest position P(AR) can increase (e.g., non-linearly)as a function of the amount of rotation of the knob 170 with respect tothe at-rest position P(AR). Additionally, the knob 170 can be configuredwith position indicating detents such that the driver can positivelyfeel the at-rest position P(AR) and feel the ends of the opposingrotational ranges of motion R(L), R(R) approaching (e.g., soft endstops).

The movement sensing device 175 is configured for sensing movement ofthe knob 170 and outputting a corresponding signal (i.e., movementsensing device signal) to the trailer assist backup input apparatus 125shown in FIG. 1. The movement sensing device signal is generated as afunction of an amount of rotation of the knob 170 with respect to theat-rest position P(AR), a rate movement of the knob 170, and/or adirection of movement of the knob 170 with respect to the at-restposition P(AR). As will be discussed below in greater detail, theat-rest position P(AR) of the knob 170 corresponds to a movement sensingdevice signal indicating that the vehicle 100 should be steered suchthat the trailer 100 is backed along a substantially straight path asdefined by a centerline longitudinal axis of the trailer 110 when theknob 170 was returned to the at-rest position P(AR) and a maximumclockwise and anti-clockwise position of the knob 170 (i.e., limits ofthe opposing rotational ranges of motion R(R), R(L)) each corresponds toa respective movement sensing device signal indicating a tightest radiusof curvature (i.e., most acute trajectory) of a path of travel of thetrailer 110 that is possible without the corresponding vehicle steeringinformation causing a jack-knife condition. In this regard, the at-restposition P(AR) is a zero curvature commanding position with respect tothe opposing rotational ranges of motion R(R), R(L). It is disclosedherein that a ratio of a commanded curvature of a path of a trailer(e.g., radius of a trailer trajectory) and a corresponding amount ofrotation of the knob can vary (e.g., non-linearly) over each one of theopposing rotational ranges of motion R(L), R(R) of the knob 170. It isalso disclosed therein that the ratio can be a function of vehiclespeed, trailer geometry, vehicle geometry, hitch geometry and/or trailerload.

Use of the knob 170 decouples trailer steering inputs from being made ata steering wheel of the vehicle 100. In use, as a driver of the vehicle100 backs the trailer 110, the driver can turn the knob 170 to dictate acurvature of a path of the trailer 110 to follow and returns the knob170 to the at-rest position P(AR) for causing the trailer 110 to bebacked along a straight line. Accordingly, in embodiments of trailerbackup assist systems where the steering wheel remains physicallycoupled to the steerable wheels of a vehicle during backup of anattached trailer, a rotatable control element configured in accordancewith the inventive subject matter (e.g., the knob 170) provides a simpleand user-friendly means of allowing a driver of a vehicle to inputtrailer steering commands.

It is disclosed herein that a rotational control input device configuredin accordance with embodiments of the inventive subject matter (e.g.,the knob 170 and associated movement sensing device) can omit a meansfor being biased to an at-rest position between opposing rotationalranges of motion. Lack of such biasing allows a current rotationalposition of the rotational control input device to be maintained untilthe rotational control input device is manually moved to a differentposition. Preferably, but not necessarily, when such biasing is omitted,a means is provided for indicating that the rotational control inputdevice is positioned in a zero curvature commanding position (e.g., atthe same position as the at-rest position in embodiments where therotational control input device is biased). Examples of means forindicating that the rotational control input device is positioned in thezero curvature commanding position include, but are not limited to, adetent that the rotational control input device engages when in the zerocurvature commanding position, a visual marking indicating that therotational control input device is in the zero curvature commandingposition, an active vibratory signal indicating that the rotationalcontrol input device is in or approaching the zero curvature commandingposition, an audible message indicating that the rotational controlinput device is approaching the zero curvature commanding position, andthe like.

It is also disclosed herein that embodiments of the inventive subjectmatter can be configured with a control input device that is notrotational (i.e., a non-rotational control input device). Similar to arotational control input device configured in accordance withembodiments of the inventive subject matter (e.g., the knob 170 andassociated movement sensing device), such a non-rotational control inputdevice is configured to selectively provide a signal causing a trailerto follow a path of travel segment that is substantially straight and toselectively provide a signal causing the trailer to follow a path oftravel segment that is substantially curved. Examples of such anon-rotational control input device include, but are not limited to, aplurality of depressible buttons (e.g., curve left, curve right, andtravel straight), a touch screen on which a driver traces or otherwiseinputs a curvature for path of travel commands, a button that istranslatable along an axis for allowing a driver to input path of travelcommands, and the like.

The trailer backup steering input apparatus 125 can be configured toprovide various feedback information to a driver of the vehicle 100.Examples of situation that such feedback information can indicateinclude, but are not limited to, a status of the trailer backup assistsystem 105 (e.g., active, in standby (e.g., when driving forward toreduce the trailer angle), faulted, inactive, etc), that a curvaturelimit has been reached (i.e., maximum commanded curvature of a path oftravel of the trailer 110), etc. To this end, the trailer backupsteering input apparatus 125 can be configured to provide a tactilefeedback signal (e.g., a vibration through the knob 170) as a warning ifany one of a variety of conditions occur. Examples of such conditionsinclude, but are not limited to, the trailer 110 having jack-knifed, thetrailer backup assist system 105 has had a failure, the trailer backupassist system 105 or other system of the vehicle 100 has predicted acollision on the present path of travel of the trailer 110, the trailerbackup system 105 has restricted a commanded curvature of a trailer'spath of travel (e.g., due to excessive speed or acceleration of thevehicle 100), and the like. Still further, it is disclosed that thetrailer backup steering input apparatus 125 can use illumination (e.g.,an LED 180) and/or an audible signal output (e.g., an audible outputdevice 185) to provide certain feedback information (e.g.,notification/warning of an unacceptable trailer backup condition).

Referring now to FIGS. 2 and 3, an example of using the trailer backupsteering input apparatus 125 for dictating a curvature of a path oftravel (POT) of a trailer (i.e., the trailer 110 shown in FIG. 1) whilebacking up the trailer with a vehicle (i.e., the vehicle 100 in FIGS. 1and 2) is shown. In preparation of backing the trailer 110, the driverof the vehicle 100 drives the vehicle 100 forward along a pull-thru path(PTP) to position the vehicle 100 and trailer 110 at a first backupposition B1. In the first backup position B1, the vehicle 100 andtrailer 110 are longitudinally aligned with each other such that alongitudinal centerline axis L1 of the vehicle 100 is aligned with(e.g., parallel with or coincidental with) a longitudinal centerlineaxis L2 of the trailer 110. It is disclosed herein that such alignmentof the longitudinal axes L1, L2 at the onset of an instance of trailerbackup functionality is not a requirement for operability of a trailerbackup assist system configured in accordance with the inventive subjectmatter.

After activating the trailer backup assist system 105 (e.g., before,after, or during the pull-thru sequence), the driver begins to back thetrailer 110 by reversing the vehicle 100 from the first backup positionB1. So long as the knob 170 of the trailer backup steering inputapparatus 125 remains in the at-rest position P(AR), the trailer backupassist system 105 will steer the vehicle 100 as necessary for causingthe trailer 110 to be backed along a substantially straight path oftravel as defined by the longitudinal centerline axis L2 of the trailer110 at the time when backing of the trailer 110 began. When the trailerreaches the second backup position B2, the driver rotates the knob 170to command the trailer 110 to be steered to the right (i.e., a knobposition R(R)). Accordingly, the trailer backup assist system 105 willsteer the vehicle 100 for causing the trailer 110 to be steered to theright as a function of an amount of rotation of the knob 170 withrespect to the at-rest position P(AR), a rate movement of the knob 170,and/or a direction of movement of the knob 170 with respect to theat-rest position P(AR). Similarly, the trailer 110 can be commanded tosteer to the left by rotating the knob 170 to the left. When the trailerreaches backup position B3, the driver allows the knob 170 to return tothe at-rest position P(AR) thereby causing the trailer backup assistsystem 105 to steer the vehicle 100 as necessary for causing the trailer110 to be backed along a substantially straight path of travel asdefined by the longitudinal centerline axis L2 of the trailer 110 at thetime when the knob 170 was returned to the at-rest position P(AR).Thereafter, the trailer backup assist system 105 steers the vehicle 100as necessary for causing the trailer 110 to be backed along thissubstantially straight path to the fourth backup position B4. In thisregard, arcuate (e.g., curved) portions of a path of travel POT of thetrailer 110 are dictated by rotation of the knob 170 and straightportions of the path of travel POT are dictated by an orientation of thecenterline longitudinal axis L2 of the trailer when the knob 170 isin/returned to the at-rest position P(AR).

FIG. 4 shows a method 200 for implementing trailer backup assistfunctionality in accordance with an embodiment of the inventive subjectmatter. In a preferred embodiment, the method 200 for implementingtrailer backup assist functionality can be carried out using the trailerbackup assist architecture discussed above in reference to the vehicle100 and trailer 110 of FIG. 1. Accordingly, trailer steering informationis provided through use of a rotational control input device (e.g., theknob 170 discussed in reference to FIG. 2).

An operation 202 is performed for receiving a trailer backup assistrequest. Examples of receiving the trailer backup assist request includeactivating the trailer backup assist system and providing confirmationthat the vehicle and trailer are ready to be backed. After receiving atrailer backup assist request (i.e., while the vehicle is beingreversed), an operation 204 is performed for receiving a trailer backupinformation signal. Examples of information carried by the trailerbackup information signal include, but is not limited to, informationfrom the trailer backup steering input apparatus 125, information fromthe hitch angle detecting apparatus 130, information from thepower-steering assist control module. 135, information from the brakesystem control module 145, and information from the powertrain controlmodule 150. It is disclosed herein that information from the trailerbackup steering input apparatus 125 preferably includes trailer pathcurvature information characterizing a desired curvature for the path oftravel of the trailer, such as provided by the trailer backup steeringinput apparatus 125 discussed above in reference to FIGS. 1 and 2. Inthis manner, the operation 204 for receiving the trailer backupinformation signal can include receiving trailer path curvatureinformation characterizing the desired curvature for the path of travelof the trailer.

If the trailer backup information signal indicates that a change incurvature of the trailer's path of travel is requested (i.e., commandedvia the knob 170), an operation 206 is performed for determining vehiclesteering information for providing the requested change in curvature ofthe trailer's path of travel. Otherwise, an operation 208 is performedfor determining vehicle steering information for maintaining a currentstraight-line heading of the trailer (i.e., as defined by thelongitudinal centerline axis of the trailer). Thereafter, an operation210 is performed for providing the vehicle steering information to apower-steering assist system of the vehicle, followed by an operation212 being performed for determining the trailer backup assist status. Ifit is determined that trailer backup is complete, an operation 214 isperformed for ending the current trailer backup assist instance.Otherwise the method 200 returns to the operation 204 for receivingtrailer backup information. Preferably, the operation for receiving thetrailer backup information signal, determining the vehicle steeringinformation, providing the vehicle steering information, and determiningthe trailer backup assist status are performed in a monitoring fashion(e.g., at a high rate of speed of a digital data processing device).Accordingly, unless it is determined that reversing of the vehicle forbacking the trailer is completed (e.g., due to the vehicle having beensuccessfully backed to a desired location during a trailer backup assistinstance, the vehicle having to be pulled forward to begin anothertrailer backup assist instance, etc), the method 200 will continually beperforming the operations for receiving the trailer backup informationsignal, determining the vehicle steering information, providing thevehicle steering information, and determining the trailer backup assiststatus.

It is disclosed herein that the operation 206 for determining vehiclesteering information for providing the requested change in curvature ofthe trailer's path of travel preferably includes determining vehiclesteering information as a function of trailer path curvature informationcontained within the trailer backup information signal. As will bediscussed below in greater detail, determining vehicle steeringinformation can be accomplished through a low order kinematic modeldefined by the vehicle and the trailer. Through such a model, arelationship between the trailer path curvature and commanded steeringangles of steered wheels of the vehicle can be generated for determiningsteering angle changes of the steered wheels for achieving a specifiedtrailer path curvature. In this manner, the operation 206 fordetermining vehicle steering information can be configured forgenerating information necessary for providing trailer path curvaturecontrol in accordance with the inventive subject matter.

In some embodiments of the inventive subject matter, the operation 210for providing the vehicle steering information to the power-steeringassist system of the vehicle causes the steering system to generate acorresponding steering command as a function of the vehicle steeringinformation. The steering command is interpretable by the steeringsystem and is configured for causing the steering system to move steeredwheels of the steering system for achieving a steered angle as specifiedby the vehicle steering information. Alternatively, the steering commandcan be generated by a controller, module or computer external to thesteering system (e.g., a trailer backup assist control module) and beprovided to the steering system.

In parallel with performing the operations for receiving the trailerbackup information signal, determining the vehicle steering information,providing the vehicle steering information, and determining the trailerbackup assist status, the method 200 performs an operation 216 formonitoring the trailer backup information for determining if anunacceptable trailer backup condition exists. Examples of suchmonitoring include, but are not limited to assessing a hitch angle todetermine if a hitch angle threshold is exceeded, assessing a backupspeed to determine if a backup speed threshold is exceeded, assessingvehicle steering angle to determining if a vehicle steering anglethreshold is exceeded, assessing other operating parameters (e.g.,vehicle longitudinal acceleration, throttle pedal demand rate and hitchangle rate) for determining if a respective threshold value is exceeded,and the like. Backup speed can be determining from wheel speedinformation obtained from one or more wheel speed sensors of thevehicle. If it is determined that an unacceptable trailer backupcondition exists, an operation 218 is performed for causing the currentpath of travel of the trailer to be inhibited (e.g., stopping motion ofthe vehicle), followed by the operation 214 being performed for endingthe current trailer backup assist instance. It is disclosed herein thatprior to and/or in conjunction with causing the current trailer path tobe inhibited, one or more actions (e.g., operations) can be implementedfor providing the driver with feedback (e.g., a warning) that such anunacceptable trailer angle condition is impending or approaching. In oneexample, if such feedback results in the unacceptable trailer anglecondition being remedied prior to achieving a critical condition, themethod can continue with providing trailer backup assist functionalityin accordance with operations 204-212. Otherwise, the method can proceedto operation 214 for ending the current trailer backup assist instance.In conjunction with performing the operation 214 for ending the currenttrailer backup assist instance, an operation can be performed forcontrolling movement of the vehicle to correct or limit a jackknifecondition (e.g., steering the vehicle, decelerating the vehicle,limiting magnitude and/or rate of driver requested trailer curvatureinput, and/or the like to preclude the hitch angle from being exceeded).

Turning now to a discussion of a kinematic model used to calculate arelationship between a curvature of a path of travel of a trailer andthe steering angle of a vehicle towing the trailer, a low orderkinematic model can be desirable for a trailer back-up assist systemconfigured in accordance with some embodiments of the inventive subjectmatter. To achieve such a low order kinematic model, certain assumptionsare made with regard to parameters associated with the vehicle/trailersystem. Examples of such assumptions include, but are not limited to,the trailer being backed by the vehicle at a relatively low speed,wheels of the vehicle and the trailer having negligible (e.g., no) slip,tires of the vehicle, vehicle lateral compliance, and the trailer havingnegligible (e.g., no) deformation, actuator dynamics of the vehiclebeing negligible, the vehicle and the trailer exhibiting negligible(e.g., no) roll or pitch motions.

As shown in FIG. 5, for a system defined by a vehicle 302 and a trailer304, the kinematic model 300 is based on various parameters associatedwith the vehicle 302 and the trailer 304. These kinematic modelparameters include:

δ: steering angle at steered front wheels 306 of the vehicle 302;

α: yaw angle of the vehicle 302;

β: yaw angle of the trailer 304;

γ: hitch angle (γ=β−α);

W: wheel base of the vehicle 302;

L: length between hitch point 308 and rear axle 310 of the vehicle 302;

D: length between hitch point 308 and axle 312 of the trailer 304; and

r₂: curvature radius for the trailer 304.

The kinematic model 300 of FIG. 5 reveals a relationship between trailerpath radius of curvature r₂ at the midpoint 314 of an axle 306 of thetrailer 304, steering angle δ of the steered wheels 306 of the vehicle302, and the hitch angle γ. As shown in the equation below, thisrelationship can be expressed to provide the trailer path curvature κ₂such that, if γ is given, the trailer path curvature κ₂ can becontrolled based on regulating the steering angle δ (where β(.) istrailer yaw rate and η(.) is trailer velocity).

$\kappa_{2} = {\frac{1}{r_{2}} = {\frac{\overset{.}{\beta}}{\overset{.}{\eta}} = \frac{{\left( {W + \frac{{KV}^{2}}{g}} \right)\sin \; \gamma} + {L\; \cos \; {\gamma tan\delta}}}{D\left( {{\left( {W + \frac{{KV}^{2}}{g}} \right)\cos \; \gamma} - {L\; \sin \; \gamma \; \tan \; \delta}} \right)}}}$

Or, this relationship can be expressed to provide the steering angle δas a function of trailer path curvature κ2 and hitch angle γ.

$\delta = {{\tan^{- 1}\left( \frac{\left( {W + \frac{{KV}^{2}}{g}} \right)\left\lbrack {{\kappa_{2}D\; \cos \; \gamma} - {\sin \; \gamma}} \right\rbrack}{{{DL}\; \kappa_{2}\sin \; \gamma} + {L\; \cos \; \gamma}} \right)} = {F\left( {\gamma,\kappa_{2},K} \right)}}$

Accordingly, for a particular vehicle and trailer combination, certainkinematic model parameters (e.g., D, W and L) are constant and assumedknown. V is the vehicle longitudinal speed and g is the acceleration dueto gravity. K is a speed dependent parameter which when set to zeromakes the calculation of steering angle independent of vehicle speed.For example, vehicle-specific kinematic model parameters can bepredefined in an electronic control system of a vehicle andtrailer-specific kinematic model parameters can be inputted by a driverof the vehicle. Trailer path curvature κ₂ is determined from the driverinput via a trailer backup steering input apparatus. Through the use ofthe equation for providing steering angle, a corresponding steeringcommand can be generated for controlling a steering system (e.g., anactuator thereof) of the vehicle.

FIG. 6 shows an example of a trailer path curvature function plot 400for a rotary-type trailer backup steering input apparatus (e.g., thetrailer backup steering input apparatus 125 discussed above in referenceto FIGS. 1 and 2). A value representing trailer path curvature (e.g.,trailer path curvature κ2) is provided as an output signal from therotary-type trailer backup steering input apparatus as a function ofuser input movement. In this example, a curve 402 specifying trailerpath curvature relative to user input (e.g., amount of rotation) at arotary input device (e.g., a knob) is defined by a cubic function.However, a skilled person will appreciate that embodiments of theinventive subject matter are not limited to any particular functionbetween a magnitude and/or rate of input at a trailer backup steeringinput apparatus (e.g., knob rotation) and a resulting trailer pathcurvature value.

Referring to FIG. 5, in preferred embodiments of the inventive subjectmatter, it is desirable to limit the potential for the vehicle 302 andthe trailer 304 to attain a jackknife angle (i.e., the vehicle/trailersystem achieving a jackknife condition). A jackknife angle γ(j) refersto a hitch angle γ that cannot be overcome by the maximum steering inputfor a vehicle, when the vehicle is reversing, such as, for example, thesteered front wheels 306 of the vehicle 302 being moved to a maximumsteered angle δ at a maximum rate of steering angle change. Thejackknife angle γ(j) is a function of a maximum wheel angle for thesteered wheel 306 of the vehicle 302, the wheel base W of the vehicle302, the distance L between hitch point 308 and the rear axle 310 of thevehicle 302, and the length D between the hitch point 308 and the axle312 of the trailer 304. When the hitch angle γ for the vehicle 302 andthe trailer 304 achieves or exceeds the jackknife angle γ(j), thevehicle 302 must be pulled forward to reduce the hitch angle γ. Thus,for limiting the potential for a vehicle/trailer system attaining ajackknife angle, it is preferable to control the yaw angle of thetrailer while keeping the hitch angle of the vehicle/trailer systemrelatively small.

Referring to FIGS. 5 and 7, a steering angle limit for the steered frontwheels 306 requires that the hitch angle γ cannot exceed the jackknifeangle γ(j), which is also referred to as a critical hitch angle. Thus,under the limitation that the hitch angle γ cannot exceed the jackknifeangle γ(j), the jackknife angle γ(j) is the hitch angle γ that maintainsa circular motion for the vehicle/trailer system when the steered wheels306 are at a maximum steering angle δ(max). The steering angle forcircular motion with hitch angle is defined by the following equation.

${\tan \; \delta_{\max}} = \frac{W\; \sin \; \gamma_{\max}}{D + {L\; \cos \; \gamma_{\max}}}$

Solving the above equation for hitch angle allows jackknife angle γ(j)to be determined. This solution, which is shown in the followingequation, can be used in implementing trailer backup assistfunctionality in accordance with the inventive subject matter formonitoring, hitch angle in relation to jackknife angle.

${{\cos \overset{\_}{\gamma}} = \frac{{- b} \pm \sqrt{b^{2} - {4{ac}}}}{2a}},$

where,

a=L ² tan² δ(max)+W ²;

b=2LD tan² δ(max); and

c=D ² tan² δ(max)−W ².

In certain instances of backing a trailer, a jackknife enablingcondition can arise based on current operating parameters of a vehiclein combination with a corresponding hitch angle. This condition can beindicated when one or more specified vehicle operating thresholds aremet while a particular hitch angle is present. For example, although theparticular hitch angle is not currently at the jackknife angle for thevehicle and attached trailer, certain vehicle operating parameters canlead to a rapid (e.g., uncontrolled) transition of the hitch angle tothe jackknife angle for a current commanded trailer path curvatureand/or can reduce an ability to steer the trailer away from thejackknife angle. One reason for a jackknife enabling condition is thattrailer curvature control mechanisms (e.g., those in accordance with theinventive subject matter) generally calculate steering commands at aninstantaneous point in time during backing of a trailer. However, thesecalculations will typically not account for lag in the steering controlsystem of the vehicle (e.g., lag in a steering EPAS controller). Anotherreason for the jackknife enabling condition is that trailer curvaturecontrol mechanisms generally exhibit reduced steering sensitivity and/oreffectiveness when the vehicle is at relatively high speeds and/or whenundergoing relatively high acceleration.

FIG. 8 shows a method 500 for implementing jackknife countermeasuresfunctionality in accordance with an embodiment of the inventive subjectmatter for a vehicle and attached trailer. Trailer backup assistfunctionality in accordance with the inventive subject matter caninclude jackknife countermeasures functionality. Alternatively,jackknife countermeasures functionality in accordance with an embodimentof the inventive subject matter can be implemented separately from otheraspects of trailer backup assist functionality.

The method 500 begins when operation 502 is performed for receivingjackknife determining information characterizing a jackknife enablingcondition of the vehicle-trailer combination at a particular point intime (e.g., at the point in time when the jackknife determininginformation was sampled). Examples of the jackknife determininginformation includes, but are not limited to, information characterizinga hitch angle, information characterizing a vehicle accelerator pedaltransient state, information characterizing a speed of the vehicle,information characterizing longitudinal acceleration of the vehicle,information characterizing a brake torque being applied by a brakesystem of the vehicle, information characterizing a powertrain torquebeing applied to driven wheels of the vehicle, and informationcharacterizing the magnitude and rate of driver requested trailercurvature. The operation 502 for receiving jackknife determininginformation can be the first operation in a sampling process wherejackknife determining information is sampled upon initiation of aninstance of implementing jackknife countermeasures functionality. Inthis regard, jackknife determining information would be continuallymonitored such as, for example, by a electronic control unit (ECU) thatcarries out trailer backup assist (TBA) functionality. As discussedabove in reference to FIG. 5, a kinematic model representation of thevehicle and the trailer can be used to determine a jackknife angle forthe vehicle-trailer combination. However, the inventive subject matteris not unnecessarily limited to any specific approach for determiningthe jackknife angle.

After receiving the jackknife determining information, an operation 504is performed for assessing the jackknife determining information fordetermining if the vehicle-trailer combination attained the jackknifeenabling condition at the particular point in time. The objective of theoperation 504 for assessing the jackknife determining information isdetermining if a jackknife enabling condition has been attained at thepoint in time defined by the jackknife determining information. If it isdetermined that a jackknife enabling condition is not present at theparticular point in time, the method 500 returns to the operation 502for receiving another instance of the jackknife determining information.If it is determined that a jackknife enabling condition is present atthe particular point in time, an operation 506 is performed fordetermining an applicable counter-measure or counter-measures toimplement. Accordingly, in some embodiments of the inventive subjectmatter, an applicable counter-measure will be selected dependent upon aparameter identified as being a key influencer of the jackknife enablingcondition. However, in other embodiments, an applicable counter-measurewill be selected as being most able to readily alleviate the jackknifeenabling condition. In still other embodiment, a pre-definedcounter-measure or pre-defined set of counter-measures may be theapplicable counter-measure(s).

The objective of a counter-measure in the context of the inventivesubject matter (i.e., a jackknife reduction countermeasure) is toalleviate a jackknife enabling condition. To this end, such acounter-measure can be configured to alleviate the jackknife enablingcondition using a variety of different strategies. In a vehicle speedsensitive counter-measure strategy, actions taken for alleviating thejackknife enabling condition can include overriding and/or limitingdriver requested trailer radius of curvature (e.g., being requested viaa trailer backup steering input apparatus configured in accordance withthe inventive subject matter) as a function of vehicle speed (e.g., viaa look-up table correlating radius of curvature limits to vehicle speedas shown in FIG. 6). In a counter-measure strategy where trailercurvature requests are limited as a function of speed and drivercurvature command transient rates, actions taken for alleviating thejackknife enabling condition can include rate limiting trailer curvaturecommand transients as requested by a driver above a pre-defined vehiclespeed whereas, under the pre-defined vehicle speed, the as-requestedtrailer curvature are not rate limited. In a torque limitingcounter-measure strategy, actions taken for alleviating the jackknifeenabling condition can include application of full available powertraintorque being inhibited when the jackknife enabling condition is presentwhile the vehicle is above a pre-defined speed and application of fullavailable powertrain torque being allowed when the vehicle speed isreduced below the pre-defined speed while in the torque inhibiting mode.As opposed to a fixed pre-defined speed, the torque limitingcounter-measure strategy can utilize a speed threshold that is afunction of hitch angle (i.e., speed threshold inversely proportional tohitch angle acuteness). In a driver accelerator pedal transientdetection counter-measure strategy, actions taken for alleviating thejackknife enabling condition can include overriding and/or limitingdriver requested trailer radius of curvature as a function of transientaccelerator pedal requests (e.g., requested trailer radius of curvaturelimited when a large accelerator pedal transient is detected). In ahitch angle, rate sensitive counter-measure strategy, actions taken foralleviating the jackknife enabling condition can include using hitchangle rate in a predefined or calculated mapping with current hitchangle position to limit driver requested trailer radius of curvature.Accordingly, in view of the disclosures made herein, a skilled personwill appreciate that embodiments of the inventive subject matter are notunnecessarily limited to a counter-measure strategy of any particularconfiguration.

As disclosed above, implementation of trailer backup assistfunctionality in accordance with the inventive subject matter canutilize a kinematic model for determining steering control information,jackknife enabling conditions, and jackknife angle. Such a kinematicmodel has many parameters than can influence trailer curvature controleffectiveness. Examples of these parameters include, but are not limitedto, the vehicle wheelbase, understeer gradient gain, vehicle trackwidth, maximum steer angle at the vehicle front wheels, minimum turningradius of vehicle, maximum steering rate able to be commanded by thesteering system, hitch ball to trailer axle length, and vehicle rearaxle to hitch ball length. Sensitivity analysis for a given kinematicmodel can be used to provide an understanding (e.g., sensitivity) of therelationships between such parameters, thereby providing informationnecessary for improving curvature control performance and for reducingthe potential for jackknife enabling conditions. For example, through anunderstanding of the sensitivity of the parameters of a kinematic model,scaling factors can be used with speed dependent jackknifecounter-measures to reduce jackknife potential (e.g., for specialapplications such as short wheelbase conditions).

Still referring to FIG. 8, after determining the applicablecountermeasure(s), an operation 508 is performed for implementing thechosen jackknife countermeasures) and an operation 510 is performed forinitiating a jackknife warning. As discussed above in regard tocounter-measure strategies, implementing the jackknifecounter-measure(s) can include commanding a speed controlling system ofthe vehicle to transition to an altered state of operation in which aspeed of the vehicle is reduced, commanding the steering control systemof the vehicle to transition to an altered state of operation in which aradius of a curvature of a path of the trailer is increased, command thesteering control system of the vehicle to transition to an altered stateof operation in which an increase in the radius of the curvature of thepath of the trailer is inhibited, commanding a brake control system ofthe vehicle to apply brake torque to reduce vehicle speed/inhibitvehicle acceleration, and/or commanding a powertrain control system ofthe vehicle to inhibit full available powertrain torque from beingdelivered to driven wheels of the vehicle until another jackknifeenabling parameter (e.g., vehicle speed) is below a defined threshold.In certain embodiments of the inventive subject matter, the jackknifewarning is provided to the driver using at least one vehicle controlsystem through which the jackknife counter-measure is implemented. Speedreduction can be accomplished by any number of means such as, forexample, limiting throttle inputs (e.g., via a terrain managementfeature) and/or transitioning a transmission to a reverse low gear ifthe vehicle is equipped with a multi-range reverse gear transmission.Examples of such system-specific warning approach include, but are notlimited to, providing a warning through an accelerator pedal of thevehicle (e.g., via haptic feedback) if the counter-measure includeslimiting speed of the vehicle and/or providing a warning through aninput element (e.g., knob) of a trailer backup steering input apparatusof the vehicle (e.g., via haptic feedback if the counter-measureincludes limiting driver requested trailer radius of curvature), throughhaptic seat vibration warning, through a visual warning (e.g., a througha visual display apparatus of the towing vehicle) and/or through aaudible warnings (e.g., through an audio output apparatus of the towingvehicle), or the like. One embodiment of utilizing warnings relating tovehicle speed as it related to onset or presence of a jackknife enablingcondition includes implementation of a dual stage warning. For example,when a backing speed of the vehicle increases sufficiently for causing aspeed of the vehicle to reach a lower (i.e., first) speed thresholdduring backing of the trailer, a driver of the vehicle would be providedwith a first warning indication (e.g., via haptic, audible, and/orvisual means as implemented by the trailer backup assist system) forinforming the driver that there is the need to reduce the speed of thevehicle to alleviate or prelude the jackknife enabling condition. If thedriver does not correspondingly respond by causing a speed of thevehicle to be reduced (or not to further increase) and the vehiclecontinues to gain speed such that it passes a higher (i.e., a second)speed threshold, the driver of the vehicle would be provided with asecond warning indication (e.g., a more severed haptic, audible, and/orvisual means as implemented by the trailer backup assist system) forinforming the driver that there is an immediate need to reduce the speedof the vehicle to alleviate or prelude the jackknife enabling condition.The first and/or the second speed indication warnings can be implementedin conjunction with a respective speed limiting counter-measure measures(e.g., the trailer backup assist system causing activation of a brakesystem of the vehicle and/or deducing a throttle position of thevehicle).

Referring now to instructions processible by a data processing device,it will be understood from the disclosures made herein that methods,processes and/or operations adapted for carrying out trailer backupassist functionality as disclosed herein are tangibly embodied bynon-transitory computer readable medium having instructions thereon thatare configured for carrying out such functionality. The instructions aretangibly embodied for carrying out the method 200 disclosed anddiscussed above and can be further configured for limiting the potentialfor a jackknife condition such as, for example, by monitoring jackknifeangle through use of the equations discussed in reference to FIGS. 5 and7 and/or by implementing jackknife countermeasures functionalitydiscussed above in reference to FIG. 8. The instructions may beaccessible by one or more data processing devices from a memoryapparatus (e.g. RAM, ROM, virtual memory, hard drive memory, etc), froman apparatus readable by a drive unit of a data processing system (e.g.,a diskette, a compact disk, a tape cartridge, etc) or both. Accordingly,embodiments of computer readable medium in accordance with the inventivesubject matter include a compact disk, a hard drive, RAM or other typeof storage apparatus that has imaged thereon a computer program (i.e.,instructions) configured for carrying out trailer backup assistfunctionality in accordance with the inventive subject matter.

In a preferred embodiment of the inventive subject matter, a trailerback-up assist control module (e.g., the trailer back-up assist controlmodule 120 discussed above in reference to FIG. 1) comprises such a dataprocessing device, such a non-transitory computer readable medium, andsuch instructions on the computer readable medium for carrying outtrailer backup assist functionality (e.g., in accordance with the method200 discussed above in reference to FIG. 2 and/or the method 500discussed above in reference to FIG. 8). To this end, the trailerback-up assist control module can comprise various signal interfaces forreceiving and outputting signals. For example, a jackknife enablingcondition detector can include a device providing hitch angleinformation and hitch angle calculating logic of the trailer back-upassist control module. A trailer back-up assist control module in thecontext of the inventive subject matter can be any control module of anelectronic control system that provides for trailer back-up assistcontrol functionality in accordance with the inventive subject matter.Furthermore, it is disclosed herein that such a control functionalitycan be implemented within a standalone control module (physically andlogically) or can be implemented logically within two or more separatebut interconnected control modules (e.g., of an electronic controlsystem of a vehicle) In one example, trailer back-up assist controlmodule in accordance with the inventive subject matter is implementedwithin a standalone controller unit that provides only trailer backupassist functionality. In another example, trailer backup assistfunctionality in accordance with the inventive subject matter isimplemented within a standalone controller unit of an electronic controlsystem of a vehicle that provides trailer backup assist functionality aswell as one or more other types of system control functionality of avehicle (e.g., anti-lock brake system functionality, steering powerassist functionality, etc). In still another example, trailer backupassist functionality in accordance with the inventive subject matter isimplemented logically in a distributed manner whereby a plurality ofcontrol units, control modules, computers, or the like (e.g., anelectronic control system) jointly carry out operations for providingsuch trailer backup assist functionality.

As discussed above, there are benefits to a trailer backup steeringinput apparatus (e.g., the trailer backup steering input apparatus 125discussed in reference to FIG. 1) configured in accordance with theinventive subject matter being self-contained and physically detachedfrom or detachable from a vehicle. Specifically, a trailer backupsteering input apparatus allows a driver of the vehicle to position orhold the trailer backup steering input apparatus at a location and/ororientation that is preferable to them. Accordingly, such aself-contained and selectively positionable trailer backup steeringinput apparatus allows a driver to dictate its placement so as tooptimize the overall effectiveness and preference in operation of theTBA system of the vehicle. In this manner, a trailer backup steeringinput apparatus configured in accordance with the inventive subjectmatter can overcome the abovementioned adverse issues that can resultfrom a trailer backup steering input apparatus being permanently mountedon the vehicle at a specific fixed location.

In one embodiment of the inventive subject matter, the trailer backupsteering input apparatus is a detachable driver interface that isconnected to the TBA system either wirelessly or through a wiredconnection. For example, such a detachable the trailer backup steeringinput apparatus can be self-contained and selectively positionable atone or more locations of the vehicle (e.g., a dedicated apparatus thatis an original equipment manufactured (OEM) supplied apparatus). In onespecific implementation of a detachable the trailer backup steeringinput apparatus, the detachable the trailer backup steering inputapparatus is configured to fit into a cup holder when in use and thenremoved when not in use (e.g., a housing of the detachable the trailerbackup steering input apparatus is complementary to that of the cupholder). In another embodiment, the trailer backup steering inputapparatus is a standalone driver that is connect to the TBA systemeither wirelessly or through a wired connection. For example, such astandalone apparatus can be self-contained device that has no physicalinterconnection with any portion of the vehicle (e.g., a dedicatedapparatus that is an original equipment manufactured (OEM) suppliedapparatus, a smartphone having a TBA path of travel command applicationrunning thereon, or the like). Wirelessly, such connection can beimplemented using a WIFI, Bluetooth, or other suitable wireless protocolto provide a signal corresponding to a driver inputted trailer path oftravel altering commands to the controller of the TBA system. A wiredconnection could connect through a USB, Serial, or other suitableconnection port of the controller of the TBA system.

Regardless of the specific configuration of such a self-containedtrailer backup steering input apparatus (e.g., knob, slider, button(s),touchscreen, etc), the trailer backup steering input apparatus willinclude a means for the driver to provide input on which direction thedriver wants to “steer” a trailer attached to their vehicle. In thisregard, the trailer backup steering input apparatus is configured forenabling the driver of a vehicle to input trailer path altering commands(i.e., a command that causes the TBA to alter a path of travel of thetrailer). As discussed above in reference to FIGS. 2 and 3, suchcommands influence a direction in which, magnitude at which, and rate atwhich a path of travel of the trailer changes.

Referring now to FIGS. 1 and 9, the trailer backup assist control module120 and the trailer backup steering input apparatus 125 can be jointlyconfigured for allowing a driver of the vehicle 100 to selectivelyconnect the trailer backup steering input apparatus 125 to the trailerbackup assist control module 120 and to selectively position the trailerbackup steering input apparatus 125 with respect to an interior space ofthe vehicle 100 (e.g., relative to the driver seat). As shown in FIG. 9,in one embodiment directed to the trailer backup steering inputapparatus 125 being self-contained and selectively placable (e.g.,located at a user defined position, located at a plurality of vehiclemanufacturer defined positions, and the like), the trailer backup assistcontrol module 120 includes a signal interface 602 and the trailerbackup steering input apparatus 125 includes a signal interface 604.Through these signal interfaces 602, 604, a trailer steering informationsignal can be provided by the trailer backup steering input apparatus125 to the trailer backup assist control module 120. In this regard,trailer steering information inputted at the trailer backup steeringinput apparatus 125 by the driver of the vehicle 100 is transmitted fromthe trailer backup steering input apparatus 125 for reception by thetrailer backup assist control module 120.

In a wired interconnection arrangement of the trailer backup assistcontrol module 120 and the trailer backup steering input apparatus 125,the signal interfaces 602, 604 are jointly configured for beingconnected through a cable 606 or similar signal carrying structure. Afirst end of the cable 606 is electrically connected through the signalinterface 604 to signal generating circuitry 607 of the trailer backupsteering input apparatus 125. A connector 608 at a second end of thecable 606 is selectively connectable to a mating connector 610 of thetrailer backup assist control module 120 for enabling the trailer backupsteering input apparatus 125 to be selectively connected to anddisconnected from the trailer backup assist control module 120. Thesignal generating circuitry 607 is configured for generating a signal asa function of driver inputted commands for causing a path of travel ofthe trailer 110 to be altered (e.g., as discussed above in reference toFIGS. 2-4).

In a wireless interconnection arrangement of the trailer backup assistcontrol module 120 and the trailer backup steering input apparatus 125,the trailer backup assist control module 120 has a wireless signaltransceiver 612 of the vehicle 100 connected thereto and the trailerbackup steering input apparatus 125 has a wireless transmitter 614coupled to the signal interface 602 thereof. The signal interfaces 602,604 are jointly configured for enabling a signal to be wirelesslytransmitted from the trailer backup steering input apparatus 125 to thetrailer backup assist control module 120. For enabling such wirelesscommunication, the wireless signal transceiver 612 and the wirelesstransmitter 614 are configured for signal transmission therebetween viaany suitable wireless protocol (e.g., WIFI, Bluetooth, etc). In such awireless implementation, the cable 606 and associated connectors 608,610 can be omitted or can be retained for use as an auxiliaryinterconnect means with respect to the wireless interconnect means.

An enclosure 616 of the trailer backup steering input apparatus 125 hasthe signal interface 604, the signal generating circuitry 607, thewireless transmitter 614, and a user interface 618 mounted thereon(e.g., housed therein). A driver of the vehicle 100 uses the userinterface 618 for inputting trailer path altering commands. Examples ofthe user interface 618 include, but are not limited to, a knob, aslider, one or more buttons, a touchscreen, and/or the like. A specificimplementation of a knob-based embodiment of the trailer backup steeringinput apparatus 125 is discussed above in reference to FIG. 2. Throughsuch mounting of the signal interface 604, the signal generatingcircuitry 607, the wireless transmitter 614, and a user interface 618 onthe enclosure 616 and the enclosure 616 being selectively detachablefrom the vehicle 100 or a non-integral component of the vehicle 100(e.g., a discrete and selectively placable unit with respect to thevehicle 100), the trailer backup steering input apparatus 125 isself-contained and is able to be selectively placed by a driver of thevehicle 100 with respect to a structure to which the trailer backupassist control module 120 is mounted.

In the preceding detailed description, reference has been made to theaccompanying drawings that form a part hereof, and in which are shown byway of illustration specific embodiments in which the inventive subjectmatter may be practiced. These embodiments, and certain variantsthereof, have been described in sufficient detail to enable thoseskilled in the art to practice embodiments of the inventive subjectmatter. It is to be understood that other suitable embodiments may beutilized and that logical, mechanical, chemical and electrical changesmay be made without departing from the spirit or scope of such inventivedisclosures. To avoid unnecessary detail, the description omits certaininformation known to those skilled in the art. The preceding detaileddescription is, therefore, not intended to be limited to the specificforms set forth herein, but on the contrary, it is intended to coversuch alternatives, modifications, and equivalents, as can be reasonablyincluded within the spirit and scope of the appended claims.

What is claimed is:
 1. A trailer backup steering input apparatus forproviding a trailer steering information signal to a trailer backupassist control module of a vehicle through a signal interface thereof,wherein the trailer steering information signal is configured forenabling the trailer backup assist control module to generate electricalsteering commands for a steering system of the vehicle as a function ofthe trailer steering information signal, the trailer backup steeringinput apparatus comprising: a user interface through which trailer pathaltering commands are inputted; a signal generator that generates thetrailer steering information signal as a function of the trailer pathaltering commands; a signal interface connectable to the signalinterface of the trailer backup assist control module for enabling thetrailer steering information signal to be transmitted from the trailerbackup steering input apparatus for reception by the trailer backupassist control module; and an enclosure having the user interface, thesignal generator, and the signal interface mounted thereon such that thetrailer backup steering input apparatus is able to be selectively placedby a driver of the vehicle with respect to a structure to which thetrailer backup assist control module is mounted.
 2. The trailer backupsteering input apparatus of claim 1 wherein the signal interfaces arejointly configured for enabling connection therebetween by a cable. 3.The trailer backup steering input apparatus of claim 2 wherein aconnector of the cable is selectively connectable to a mating connectorof the trailer backup assist control module for enabling the trailerbackup steering input apparatus td be selectively connected to anddisconnected from the trailer backup assist control module.
 4. Thetrailer backup steering input apparatus of claim 1 wherein the signalinterfaces are jointly configured for enabling a signal to be wirelesslytransmitted from the trailer backup steering input apparatus to thetrailer backup assist control module.
 5. The trailer backup steeringinput apparatus of claim 1 wherein the user interface comprises atouchscreen through which trailer path altering commands are inputted.6. The trailer backup steering input apparatus of claim 1 wherein thesignal interfaces are jointly configured for enabling a signal to bewirelessly transmitted from the trailer backup steering input apparatusto the trailer backup assist control module.
 7. The trailer backupsteering input apparatus of claim 1 wherein: the user interface includesa knob; the signal generator includes a knob movement sensing devicecoupled to the knob for sensing movement of the knob; the knob is biasedto an at-rest position between opposing rotational ranges of motion; andthe knob movement sensing device outputs a signal generated as afunction of at least one of an amount of rotation of the rotationalcontrol input device with respect to the at-rest position, a ratemovement of the rotational control input device, and a direction ofmovement of the rotational control input device with respect to theat-rest position.
 8. The trailer backup steering input apparatus ofclaim 7 wherein: the signal interfaces are jointly configured forenabling connection therebetween by a cable; and a connector of thecable is selectively connectable to a mating connector of the trailerbackup assist control module for enabling the trailer backup steeringinput apparatus to be selectively connected to and disconnected from thetrailer backup assist control module.
 9. The trailer backup steeringinput apparatus of claim 8 wherein the signal interfaces are jointlyconfigured for enabling a signal to be wirelessly transmitted from thetrailer backup steering input apparatus to the trailer backup assistcontrol module.
 10. A trailer backup assist system, comprising: atrailer backup assist control module having a set of instructionstangibly embodied on a non-transitory processor-readable medium thereof,wherein the set of instructions is accessible from the non-transitoryprocessor-readable medium by at least one data processing device of theelectronic controller system for being interpreted thereby, and whereinthe set of instructions is configured for causing the at least one dataprocessing device to carry out operations for: receiving trailer pathcurvature information characterizing a desired curvature for a path oftravel of a trailer during backing of the trailer by a vehicle towablycoupled thereto, wherein the trailer path curvature information includestrailer steering information and trailer angle information; determiningvehicle steering information through assessment of kinematicalinformation of a system defined by the vehicle and the trailer, whereinassessment of the kinematical information is performed as a function ofthe trailer path curvature information; and generating a steeringcommand for a steering system of the vehicle as a function of thevehicle steering information; and a trailer backup steering inputapparatus for providing the trailer steering information to the trailerbackup assist control module, wherein the trailer backup steering inputapparatus is self-contained and electronically connectable to thetrailer backup assist control module in a manner enabling selectiveplacement of the trailer backup steering input apparatus by a driver ofthe vehicle with respect to a structure to which the trailer backupassist control module is mounted.
 11. The trailer backup assist systemof claim 10 wherein: the trailer backup steering input apparatus isconnected to the trailer backup assist control module through by acable; and a connector of the cable is detachable from a matingconnector of the trailer backup assist control module for enabling thetrailer backup steering input apparatus to be selectively connected toand disconnected from the trailer backup assist control module.
 12. Thetrailer backup assist system of claim 10 wherein the trailer backupsteering input apparatus is connected to the trailer backup assistcontrol module through a wireless connection
 13. The trailer backupassist system of claim 10 wherein: the trailer backup steering inputapparatus includes a user interface comprising a touchscreen throughwhich trailer path altering commands can be inputted by a driver of thevehicle; and the trailer steering information is generated as a functionof the trailer path altering commands.
 14. The trailer backup assistsystem of claim 10 wherein: the trailer backup steering input apparatusincludes a knob and a knob movement sensing device coupled to the knobfor sensing movement of the knob, wherein the trailer steeringinformation is generated by the trailer backup steering input apparatusas a function of the movement of the knob; the knob is biased to anat-rest position between opposing rotational ranges of motion; and theknob movement sensing device outputs a signal generated as a function ofat least one of an amount of rotation of the rotational control inputdevice with respect to the at-rest position, a rate movement of therotational control input device, and a direction of movement of therotational control input device with respect to the at-rest position.15. The trailer backup assist system of claim 14 wherein: the trailerbackup steering input apparatus and the trailer backup assist controlmodule are jointly configured for being connected to each other by acable for enabling the trailer steering information to be transmittedfrom the trailer backup steering input apparatus for reception by thetrailer backup assist control module; and a connector of the cable isdetachable from a mating connector of the trailer backup assist controlmodule for enabling the trailer backup steering input apparatus to beselectively connected to and disconnected from the trailer backup assistcontrol module.
 16. The trailer backup assist system of claim 14 whereinthe trailer backup steering input apparatus and the trailer backupassist control module are jointly configured for being connected to eachother through a wireless connection for enabling the trailer steeringinformation to be transmitted from the trailer backup steering inputapparatus for reception by the trailer backup assist control module. 17.A vehicle, comprising: a trailer backup assist control module forgenerating electrical steering commands as a function of trailer pathcurvature information, wherein the trailer path curvature informationcharacterizes a desired curvature for the path of travel of a trailerduring backing of the trailer by a vehicle towably coupled thereto,wherein the trailer path curvature information includes trailer steeringinformation and trailer angle information, and wherein the trailerbackup assist control module includes a signal interface for receivingthe trailer steering information; a steering system coupled to thetrailer backup assist control module for receiving steering assistcontrol signals therefrom, wherein the steering system controlsactuation mechanisms thereof as a function of the steering assistcontrol signals; and a trailer backup steering input apparatus forproviding the trailer steering information to the trailer backup assistcontrol module through the signal interface, wherein the trailer backupsteering input apparatus is self-contained and electronically connectedto the trailer backup assist control module in a manner enablingselective placement of the trailer backup steering input apparatus by adriver of the vehicle with respect to a structure of the vehicle towhich the trailer backup assist control module is mounted.
 18. Thevehicle of claim 17 wherein: the trailer backup steering input apparatusis connected to the trailer backup assist control module through by acable; and a connector of the cable is detachable from a matingconnector of the trailer backup assist control module for enabling thetrailer backup steering input apparatus to be selectively connected toand disconnected from the trailer backup assist control module.
 19. Thevehicle of claim 17 wherein the trailer backup steering input apparatusis connected to the trailer backup assist control module through awireless connection
 20. The vehicle of claim 17 wherein the trailerbackup steering input apparatus includes a user interface comprising atouchscreen through which the trailer steering information is inputtedby a driver of the vehicle.
 21. The vehicle of claim 17 wherein: thetrailer backup steering input apparatus includes a knob and a knobmovement sensing device coupled to the knob for sensing movement of theknob, wherein the trailer steering information is generated by thetrailer backup steering input apparatus as a function of the movement ofthe knob; the knob is biased to an at-rest position between opposingrotational ranges of motion; and the knob movement sensing deviceoutputs a signal generated as a function of at least one of an amount ofrotation of the rotational control input device with respect to theat-rest position, a rate movement of the rotational control inputdevice, and a direction of movement of the rotational control inputdevice with respect to the at-rest position.
 22. The vehicle of claim 21wherein: the trailer backup steering input apparatus and the trailerbackup assist control module are jointly configured for being connectedto each other by a cable for enabling the trailer steering informationto be transmitted from the trailer backup steering input apparatus forreception by the trailer backup assist control module; and a connectorof the cable is detachable from a mating connector of the trailer backupassist control module for enabling the trailer backup steering inputapparatus to be selectively connected to and disconnected from thetrailer backup assist control module.
 23. The vehicle of claim 21wherein the trailer backup steering input apparatus and the trailerbackup assist control module are jointly configured for being connectedto each other through a wireless connection for enabling the trailersteering information to be transmitted from the trailer backup steeringinput apparatus for reception by the trailer backup assist controlmodule.